CD4 and infection: ➢ It is important to encode as many immunogens as possible to elicit T cell immunity as broadly as possible to highly conserved regions of HIV-1 such as Gag and Pol.➢ The caveat is that encoding variable regions of HIV-1 in a vaccine could drive immunodominant T cell responses to variable regions of the virus. Expansion of CD4+ T cell responses that target variable regions of HIV-1 could also contribute to diminishing the efficacy of a vaccine as they will be targets for infection.